This month’s sell-off in the bond markets is already a landmark event. The fall in bond prices, both in the US and Europe, has been as sharp as any seen this decade. The consequent rise in yields has forced investors to re-examine the cosy assumptions that have underpinned the cheap financing available across the world for the past few years.

Now the question is how great the impact will be. US Treasury bond yields in effect set the “risk-free” rate used when pricing securities – from corporate credit through derivative contracts to equities – across the world. They form the financial world’s clearest expression of risk.